As is known, a centrifugal compressor is a machine which returns a compressible fluid at a higher pressure than that at which it received it, giving it the necessary energy for the pressure change, by the use of a rotor with one or more impellers.
Each impeller, which is connected to the rotor, comprises a certain number of blades, radially arranged, which transfer energy to the gas. The centrifugal step also comprises stator parts which contribute to converting the kinetic energy of the impeller into gas pressure energy and cause the gas flow in the compressor.
The gas compression area is delimited by walls, generally flanges, which support gas seals suitable for preventing the pressurized gas from leaving the compressor.
After compression, the temperature of the gas at the compressor delivery can reach a high value; this envisages an extremely accurate selection of the materials and particularly of the gas seal materials.
When the temperatures at the compressor delivery are higher than 200° C., there is a sudden perishing of the washers, O-rings and vital parts of the gas seal.
Furthermore, in some chemical and petrochemical processes, in addition to reaching an extremely high temperature at the delivery, about 275° C., the gas treated is also harmful and for this reason must absolutely remain inside the pressurized parts.
It has so far appeared to be impossible to block this harmful gas due to this perishability, as a result of the high temperature, of the vital parts of the gas seal.
It is therefore necessary to find a device which creates an acceptable environment for the gas seal in the case of high temperatures.